I have always said that this was the case. My Cousin is in the CG and he had explained to me that all the test were done with 2 up and full of fuel.
He had also said that the ski's in perfect conditions did go a bit faster, but they test them in more of a real world family setting.

And I for one know he has a inside scoop.

My RXP did not do more than 65 when full and me and the wife on it. (STOCK)